Fix performance tool flag declaration in test

For some reasons, after PicoCLI upgrade to 4.6.3, using
explicitly "true" to set the monitoring flags would trigger
a validation error when launching the test (only on Maven!).
This commit fixes this strange issue by just adding the flag
to the command line.

Author: acogoluegnes

src/test/java/com/rabbitmq/stream/perf/StreamPerfTestTest.java

@@ -321,9 +321,9 @@ void monitoringShouldReturnValidEndpoint() throws Exception {
         run(
             builder()
                 .deleteStreams()
-                .monitoring(true)
+                .monitoring()
                 .monitoringPort(monitoringPort)
-                .prometheus(true));
+                .prometheus());
     waitUntilStreamExists(s);
     waitOneSecond();
 
@@ -520,8 +520,8 @@ ArgumentsBuilder producerNames(String pattern) {
       return this;
     }
 
-    ArgumentsBuilder monitoring(boolean monitoring) {
-      arguments.put("monitoring", String.valueOf(monitoring));
+    ArgumentsBuilder monitoring() {
+      arguments.put("monitoring", "");
       return this;
     }
 
@@ -530,8 +530,8 @@ ArgumentsBuilder monitoringPort(int port) {
       return this;
     }
 
-    ArgumentsBuilder prometheus(boolean prometheus) {
-      arguments.put("prometheus", String.valueOf(prometheus));
+    ArgumentsBuilder prometheus() {
+      arguments.put("prometheus", "");
       return this;
     }